I think it would look odd to have a sofa in front of a mantel. A console table or a shelf above it might be OK. Why is the couch so far from the wall--it doesn't appear to be a hallway or anything. Pushing it back and rearranging a little will make the room feel less narrow and cramped, and you'll have room for a sidechair next to the little round table.

I think the doorway would look better if it was centered and flanked by the bookcases, and didn't have the angled corners, but I don't know what the floorplan is or anything.